New videoscope

I am using the videoscope on the timeline and the improvements are most welcome, especially the vectorscope which is now much more easily readable. However the colours have rotated about 45 degrees anticlockwise, putting, for example, green where cyan is expected and magenta where red normally is. Perfectly useable, just a bit odd, a bit like the old Cin-CV vectorscope.

The color problem is fixed and will be in the next build set on April 30th. Other changes were made to add the I-line and for an alternative vectorscope. If anyone wants an early test, we can create a static tar for a particular distro.

Thanks for the feedback on the Videoscope. We are still working to improve it and gg has looked at the original HV version to see what the differences may be. It is possible that either merging in the CV mods a few years ago or some changes may have caused a potential problem that we will try to figure out.

The Vectorwheel has allowed me to identify a problem with my colour correction, which turns out to be a glitch in the Histograms.

Using either Histogram to set black and white points prior to setting saturation, I find excess blue showing on the scope and the red/yellow shows decreased levels i. e. the colour balance is skewed towards blue. Resetting Histogram centres it again. My attempts to rebalance it have failed. It is not a scope fault as if I use Colour3Way it does not happen.

I can go back as far as 20190531 to see if it is there if you like, I can also attach screenshots. Again, if you like.

We are totally stuck and do not like to leave possible bugs out there. Some effort has been made to understand the problem by a couple of people to include gg. To determine if there is a fixable problem, more detailed information is probably needed but if you are not concerned about a fix and do not have time for this, that is OK too.

Some additional helpful information may be:

- add HistogramRGB and WaveformRGB in Videoscope tool which have more info

- a video screencast creating the issue shown

Igor Beg had the following to say: "Color3Way and Histogram (and Histogram Bezier) are different tools. I think, you can not compare the two tools. Histogram changes more parameters with an only touch: Contrast, Saturation, and Luminance. Sometimes it is better to change the values of the three channels (Red, Green, Blue) separately than change only the Value channel.The Value parameter in Histogram do not change only the luminance."

Is is possible that there is some confusion about it changing more than the luminance?

In the meantime, in response to Igor's comments, I have also compared with both Kdenlive and Shotcut (which I didn't really want to mention here because it's a bit like comparing apples to oranges) and neither of them exhibit the same blue peak. I understand the Value setting changes more than just luminance, but this excess blue in some clips is something new to me. I didn't spot it with the old Vectorscope, but it is so obvious on the VectorWheel and it explains why some clips finish up with very low saturation.

I have been experimenting with Histogram and have discovered how powerful a colour correction tool it is and yes, I have discovered that changing the RGB values in HIsto is often better. Previously I used Colour Balance or the Colour 3 Way colour wheels to try to balance up after Histo Value.

FYI I am working on 3840 x 2160p F-Log footage, HEVC 4:2:0 10-bit at 200Mbps, straight to the timeline, RGBA-FLOAT.

This morning I first decided to do more tests and check Cin Preferences/Appearance settings which, apart from changing the theme, have not been touched in a while.

The first thing I noticed was that when enabling Histogram, which had been reset, the blue level on the VectorWheel increased. Saturation had been disabled. Odd.

In Appearance I reset YUV colour range to MPEG while watching the VWheel, then back to JPEG, then reset YUV colour range from BT709 to BT601 and BT2020, again watching the VW, then set it back to BT709. BT601 did reduce the blue, but I am using a log to BT709 LUT which is why I set it back. Now, inexplicably, the blue boost when enabling Histo does not happen. I also booted up openSUSE, tried it on there and it was OK. So whatever it was, thanks for helping me sort my problem.